The "city" had nothing to do with the decision by a private sector entity to mitigate risks and propose a 54s rental tower. Given the federal tax structure with respect the GST treatment of rental housing, lack of ability to defer capital gains & recaptured depreciation deductions upon the disposition of rental properties and the "big one" on federal treatment of capital cost allowances... building purpose built rental is extremely risky which is why we see very little purpose built rental in the city. This "54 storey stump" as you've called it and suggested that city council or bureaucratic meddling has caused a reduction in height is a strange analysis given the fact that the proponent is proposing to construct the tallest ever purpose built rental tower in the city (Manulife built in 1972 is if I remember correctly currently the tallest purpose built rental tower in the city).
I'm going to suggest that for most proposals within the downtown core (and by extension the Yorkville area) that while planning context is critical (and the context here is two neighbouring taller approved buildings than what is being proposed on this site - they could have proposed and likely secured approvals for a taller building if they wanted to - they chose not to...) financial feasibility, return on investment and acceptable risks have far more to do with the proposal that you are so disappointed in than meddling bureaucrats. I would again point out that the proposal is purpose built rental - frankly I'm surprised they would propose such a large project given the federal tax laws surrounding investment in new purpose-built rental housing - this is a fairly high risk proposal as this scale.